The present invention relates to a scroll-type compressor having a mechanism for preventing seizure of bearing for an orbiting scroll.
Various scroll-type compressors relating to the present invention have been proposed, and one example thereof is shown in FIG. 8. In this figure, in a closed housing 8, a scroll-type compressing mechanism C is housed at the upper part thereof and an electric motor M at the lower part thereof. The compressing mechanism C is connected to the electric motor M via a rotating shaft 5 so as to be driven by the electric motor M. The scroll-type compressing mechanism C includes a fixed scroll 1, an orbiting scroll 2, a rotation checking mechanism 3 such as an Oldham""s ring, which permits orbital motion of the orbiting scroll 2 but checks rotation thereof, a frame 6 to which the fixed scroll 1 is fastened, and an upper bearing 71, which pivotally supports the rotating shaft 5.
The fixed scroll 1 has an end plate 11 and a spiral wrap 12 extending downward from the lower surface of the end plate 11. The end plate 11 is provided with a discharge port 13, which is formed by penetrating the end plate 11, and a discharge valve 17 for opening/closing the discharge port 13. The orbiting scroll 2 has an end plate 21 and a spiral wrap 22 extending upward from the upper surface of the end plate 21. The two spiral wraps 12 and 22 are lapped in the radial direction. In a cylindrical boss 23 provided so as to extend downward from the lower surface of the end plate 21, an eccentric bush 54 is rotatably inserted via an orbiting bearing 73. Into a hole 55 defined by the eccentric bush 54, an eccentric pin 53 protruding from the top end of the rotating shaft 5 is rotatably fitted. By engaging the spiral wraps 12 and 22 with each other so that the fixed scroll 1 and the orbiting scroll 2 are made off-centered by a predetermined distance and the angle thereof is shifted 180 degrees, a plurality of closed spaces 24 are formed. The spiral wraps 12 and 22 which form such closed spaces 24 are shown in FIG. 7 of Japanese Patent Provisional Publication No. 7-63174 (No. 63174/1995), for example.
The frame 6 is fixed in the closed housing 8, and the thrust surface 65 formed on the upper surface of the frame 6 is in slidable contact with the lower surface of the orbiting scroll 2 so that the orbiting scroll 2 is supported by the frame 6. The thrust surface 65 is formed with an annular oil groove 66. A hole circular in transverse cross section formed at the center of the upper surface of the frame 6 is closed by the lower surface of the orbiting scroll 2, thereby defining an oil reservoir 61. At the lower part of the inner wall surface of the frame 6, which defines the oil reservoir 61, is formed a oil discharge hole 62 so as to be inclined downward toward the outside in the radial direction.
A positive-displacement oil pump 51 is installed at the lower end of the rotating shaft 5. A suction pipe 56 is connected to a suction port (not shown) of the oil pump 51, and the tip end thereof is open in an oil sump 81 at the bottom of the closed housing 8. A discharge port (not shown) of the oil pump 51 is connected to an oil supply hole 52 formed in the rotating shaft 5 in the axial direction.
By driving the electric motor M, the orbiting scroll 2 is driven via an orbital motion mechanism consisting of the rotating shaft 5, eccentric pin 53, eccentric bush 54, boss 23, etc. The orbiting scroll 2 performs orbital motion in the circular orbit with the orbiting radius while the rotation is checked by the rotation checking mechanism 3.
By this motion, suction gas enters the closed housing 8 through a suction pipe 82, being introduced into a suction passage 15 through a gas passage 85, and sucked into the aforesaid closed spaces 24. The suction gas reaches the central portion of the spiral wraps 12, 22 while being compressed as the volume of the closed space 24 is decreased by the orbital motion of the orbiting scroll 2, goes out through the discharge port 13, and enters the discharge cavity 14 by pushing and opening the discharge valve 17, being discharged from the discharge cavity 14 through a discharge pipe 83.
On the other hand, since the oil pump 51 is also driven at the same time the electric motor M is driven, lubricating oil stored in the oil sump 81 at the bottom of the closed housing 8 is sucked via the suction pipe 56, being sent to the oil supply hole 52. The lubricating oil flows upward in the oil supply hole 52. Some of the lubricating oil branches halfway from the main flow to lubricate a lower bearing 72 and the upper bearing 71, and the main flow spouts from an opening of the oil supply hole 52 formed at the tip end of the eccentric pin 53 to lubricate the eccentric pin 53 and the orbiting bearing 73, and enters the oil reservoir 61. Subsequently, the lubricating oil passes through the oil groove 66 to lubricate sliding parts such as the thrust surface 65 and the rotation checking mechanism 3. Also, some of the lubricating oil entering the oil reservoir 61 drops through the oil discharge hole 62, passes through a passage 9 formed between the outer periphery of the stator of the electric motor M and the closed housing 8, and then is stored in the oil sump 81.
FIG. 9 is a view for illustrating the relationship between the eccentric bush 54 and the eccentric pin 53 in the above-described scroll-type compressor, being viewed from the upside, and FIG. 10 is a sectional view for illustrating the relationship, viewed from the side. A flat portion of the eccentric bush 54 shown in the figure abuts on a flat portion at the outer periphery of the eccentric pin 53, so that the eccentric bush 54 rotates integrally with the eccentric pin 53. The lubricating oil discharged from the oil supply hole 52 is supplied to an oil supply path 57 defined between the flat portion formed at the outer periphery of the eccentric bush 54 as shown in the figure and the orbiting bearing 73. Some of the lubricating oil is also supplied to a gap 58 formed between the outer periphery of the eccentric pin 53 necessary for the orbiting scroll 2 to perform orbital motion and the inner periphery of the eccentric bush 54, and is introduced from the gap 58 to the oil reservoir 61.
In the above-described scroll-type compressor, the lubricating oil discharged from the oil supply hole 52 in the eccentric pin 53 is distributed to the oil supply path 57 and the gap 58. The lubricating oil going out from the oil supply hole 52 on the top end face of the eccentric pin 53 enters a concave 53a defined between the upper outer peripheral surface of the eccentric pin 53 and the inner peripheral edge of the eccentric bush 54. From the concave 53a, some of the lubricating oil flows toward the oil supply path 57, and some thereof enters the gap 58. The oil distributed to the oil supply path 57 is supplied to the orbiting bearing 73 having a high sliding speed, and the oil distributed to the gap 58 is supplied to the flat portion of the eccentric pin having a low sliding speed; however, most of the lubricating oil drops into the oil reservoir 61. Therefore, for the orbiting bearing 73 having a high sliding speed, the amount of oil in the oil supply path 57 is smaller than the necessary amount, so that there is a possibility for seizure of the bearing 73 to occur.
The present invention was made in view of the above situation, and accordingly an object thereof is to provide a scroll-type compressor which solves the above problem and can supply sufficient lubricating oil without the occurrence of seizure of bearing.
To achieve the above object, the present invention provides a scroll-type compressor comprising a closed housing having a gas inlet and outlet; a support frame fixed in the closed housing; a scroll-type compressing mechanism which has a fixed scroll and a orbiting scroll disposed above the support frame and engaging with each other, fastens the fixed scroll to the support frame, and supports the orbiting scroll by bringing the orbiting scroll into slidable contact with the support frame; a rotating shaft which is disposed below the scroll-type compressing mechanism, extends upward by penetrating the support frame, and is fitted in a boss of the orbiting scroll at an eccentric pin portion at the upper end via an eccentric bush and a bearing; an electric motor for driving the orbiting scroll via the rotating shaft; and an oil pump provided at the lower end of the rotating shaft, wherein a gap is formed between the outer peripheral surface of the eccentric pin portion and the inner peripheral surface of the eccentric bush to permit the orbiting motion of the orbiting scroll, the oil supply path extending in the axial direction is provided between the outer peripheral surface of the eccentric bush and the inner peripheral surface of the bearing, and the rotating shaft and the eccentric pin portion are formed with an oil supply hole, which communicates with the oil pump and is open at the upper end face of the eccentric pin portion, so that lubricating oil is allowed to pass through the oil supply hole by the drive of the oil pump and supplied to the bearing, and the lubricating oil flowing out of the oil supply hole is supplied to the bearing via the oil supply path and supplied to a space between the support frame and the orbiting scroll.
According to a first embodiment of the present invention, a part of the upper end face of the eccentric bush is formed with a protrusion extending upward in the axial direction from other flat portion of the upper end face of the eccentric bush on the upstream side with respect to the direction of rotation of the rotating shaft, with the peripheral end of an outer peripheral oil supply path on the upstream side with respect to the direction of rotation of the rotating shaft being almost the base point. If a protrusion is formed limitedly in such a manner, the lubricating oil flowing out of the oil supply hole at the upper end face of the eccentric bush easily flows on the flat portion of the upper end face in the outer peripheral direction under the action of centrifugal force, so that the amount of lubricating oil to the oil supply path increases, which contributes to the prevention of seizure of bearing. In accordance with one aspect of the invention, it is preferable that the protrusion be formed substantially over a half of circumference of the upper end face of the eccentric pin portion.
Also, according to a second embodiment of the present invention, in the above-described scroll-type compressor, the upper end face of the eccentric bush is formed with an inner peripheral portion along the upper edge of the inner peripheral surface of the eccentric bush substantially over the whole circumference as a protrusion extending upward in the axial direction from the flat outer peripheral portion along the upper edge of the outer peripheral surface of the eccentric bush. If the protrusion is formed in such a manner, the lubricating oil flowing out of the oil supply hole at the upper end face of the eccentric bush goes beyond the protrusion under the action of centrifugal force, enters a concave formed consequently between the protrusion and the bearing, and is directed surely from here to the oil supply path, which contributes to the prevention of seizure of bearing.
Further, according to a third embodiment of the present invention, an annular flat plate member is provided between the lower end face of the eccentric bush and the upper end face of the rotating shaft so as to cover the gap from the downside. Since the bottom of the gap is substantially closed by this flat plate member, the amount of lubricating oil entering this gap is at a constant minimum, so that the supply amount to the oil supply path increases further.
The effects of the present invention are as described below.
As described above, according to the first embodiment of the present invention, the flow of lubricating oil into the gap between the outer periphery of the eccentric pin and the inner periphery of the eccentric bush, which is necessary for the orbiting scroll to perform the orbital motion, is limited. Therefore, the amount of lubricating oil supplied to the oil supply path for the orbiting bearing increases significantly, so that the seizure of the orbiting bearing and eccentric bush can be prevented effectively.
In particular, where, the protrusion is formed substantially over a half of circumference of the upper end face of the eccentric bush, the lubricating oil striking the protrusion can be guided effectively to the oil supply path, so that the oil supply amount is further increased, which contributes to the prevention of seizure.
Also, if, as in the second embodiment of the present invention, the upper end face of the eccentric bush is formed with an inner peripheral portion along the upper edge of the inner peripheral surface of the eccentric bush substantially over the whole circumference as a protrusion extending upward in the axial direction from the flat outer peripheral portion along the upper edge of the outer peripheral surface of the eccentric bush, the oil supply amount to the oil supply path is further increased, so that the prevention of seizure can further be achieved.
Further, if, as in the third embodiment of the present invention, an annular flat plate member is provided between the lower end face of the eccentric bush and the upper end face of the rotating shaft so as to cover the gap between the outer peripheral surface of the eccentric pin portion and the inner peripheral surface of the eccentric bush from the downside, the lubricating oil does not substantially drop into an oil reservoir even if the lubricating oil flows into the gap. Therefore, the amount of lubricating oil entering the gap is at a minimum, so that the supply amount to the oil supply path is further increased, by which the seizure can be prevented more preferably.